Relay circuit



0d. 4, 1949. d N. GARBER 2,483,408

RELAY CIRCUIT Filed March 26, .1945

A TTOPIVEY Patented Oct. 4, 1,949

r met RELAY CIRCUIT Nathan `Garber, Brooklyn, N Y., assgnor to Fed.-

eral Telephone land IRadio'Corporation, New York, N. Y., a corporation of Delaware Application March 26, 1945, Serial No. 584;'947

This invention relates .to more particularly Ito an arrangement .of multiple relays wherein the operation of a slave relay is controlled by the operation zof another .or master relay.

In somecontrol applications, as for instance such as disclosed in the copending applications of L. Dubin 5, Ser. No. 584,957, led March 26, 1945, and D.. D, Grieg- A. yFrum-L. Dubin, ser. No. 584,862, filed March 26, 1945, now Patent No. 2,444,439, issued July 6, 1948, which describe aspects of a radio beacon system, it becomes desirous to operate a given .circuit momentarily while operating Yanother -circuit over a .given period. 'This is the .case in theabove-mentioned applications when, .upon the appearance of a beam signal at the beacon receiver, certain integrating condensers .or .other circuits are 'to be cleared of any previous char-ge prior to receiving the charge due tothe new signal, while a circuit from the plate voltage supply to thedetector circuits, which renew the charge on the condensers, is maintained closed for the duration of the beam signal.

It is accordingly an object of this invention to provide a multiple control circuit which 4makes it possi-ble to oper-ate one Vcircuit temporarily upon theA operation of another circuit under certain conditions over a given period.

It is a further object to provide a multiple relay circuit wherein a master relay controlling one circuit, causes a slave relay to operate momentarily with respect to another circuit.

It is still another object to provide a relay circuit which causes the momentary operation of a relay upon application of relatively continuous energy.

ln accordance with a feature of the invention, a control circuit is arranged such, that when energy is applied thereto, a master relay is made to close its contacts which control the energizing circuit ior a second or slave relay. Upon closure of this energizing circuit, a transient surge is caused to pass thru the slave relay. The slave relay has a return circuit to ground which provides a time constant and which is of such a character as to permit the temporary operation only of the second relay on the occurrence of a positive surge upon closing of the first or master relay.

These and other features and objects of the invention will be better understood in connection with the detailed description of the drawings, in which:

3 claims. (c1. irs-32,0)

relay circuits and Fig. l is a circuit shown in .diagrammatic form incorporating my invention;

2 is a simplified form of a portion vof the circuit of Fig. 1-; and

Fig. 3 is agraphic representation vof some .of the operating characteristics of the circuits of Figs. l and 2. t

Referring to Fig. 1 the circuit shown therein comprises an ,amplier I which is .adapted to receive a signal from .a source which is not shown. The ainplied signal, preferably in the form .of a D. C. pulse, is applied to a master relay 2, the circuit being completed thru a voltage .source 3 to ground at Il. The voltage source 3 also serves as ,a plate voltage supply B-lfor the amplier I thru the windings .of ,tghe relay 2. The relay 2 `may control, by way of lthe contact 5, energy from the Voltage vSource 3 through any circuit which :is to be energized as indicated at E, and also a circuit `from the source 3 .to .a second or slave relay l. The relay l is provided with a .return circuit to ground at 8 which includes a resistor 9 and a condenser. IG connected in par.- .allel and adapted to introduce a time factor into the relay circuit as will appear hereinbelow. The slave relay 'I, by way of a contact I I may control a circuit of its own such vas a by-pass to ground vat 8 of a condenser I2, normally being charged with respect to the ground 8 from a charging .source (not shown) over a conductor I3. The condenser I2 or other circuit controlled by contact II may be separate from circuit 6 or it may in some way be associated therewith as indicated.

In order to be able to render more simple the discussion of the operation of the slave relay, its circuit, including the relay 1, the resistor 9, the capacitor I0, the source of voltage 3 and the control 5 have been illustrated in Fig. 2 as a separate equivalent circuit. In this equivalent circuit the relay 1 has been shown to be comprised of an inductance L and a resistance R1 the resistor 9 and the capacitor I0 having been referred to as R and C, respectively.

As the Voltage from source 3 is applied to the relay circuit of Fig. 2 by the closing of the switch 5, a transient current surge is provided in the relay L-R as at iT in Fig. 3. The current at rst builds up" rather rapidly, as determined by the values of L and C, until it reaches a point at I4 when the relay 'I closes. As the voltage across C continues to build up, the rate of build up being determined by R and R1, and as the voltage across L continues to decline, a maximum current flow thru the relay is reached as indicated at I5. The current thereafter begins to decrease because of the overbalance of the voltage of C over the voltage drop across the relay. After reaching a peak at I5, the current begins to decline exponentially to reach a point substantially at I6 When it becomes too small to hold the relay any longer and the relay opens. The relay current continues to decline due to a continuous build up of the voltage across C to approach asymptotically a steady state value i0, which is a function of the circuit resistance and may be expressed by The time interval t@ between points f4 and I6, i. e., between closing and opening, is determined by the constants of R and C, which are chosen tovr effect a given suitable operating period for the relay.

Upon removal of the energy operating the master relay, its contact will break and another transient will be produced in the slave relay. This transient, however, is of insufficient amplitude and/or duration to operate the relay 1. Upon again applying a control voltage to operate the relay 2, the cycle recited above will then be repeated.

In choosing the values of R and C, care should be taken that their values are such that together with L and R1 they do not form an oscillatory circuit. Consideration is also to be given to the choice of R so that the steady state relay current io is held to a value which is below the point i6 When the relay opens.

It is to be noted that the curves in Fig. 3 are approximate in the respect that no consideration has been given to the change in L due to closing of the relay, i. e., due to a change in the position of the relay armature. However, the principles of operation as outlined, are not aiTected thereby.

It is to be understood, of course, that the specific description of the particular embodiment is given above merely by Way of illustration and is not to be considered as a limitation of my invention as set forth in the objects thereof and in the appended claims.

I claim:

1. A control system comprising a master relay having a cooperating contact, a slave relay, a source of potential for energizing said slave relay, a timing circuit including a resistor and a condenser connected in parallel, said contact, said slave relay, said source and said circuit all serially connected, a source of direct current pulses for momentarily energizing said master relay for prescribed periods of time, said contact controlling the operation of said slave relay and said circuit controlling the reduction of eiective current through said slave relay to deenergize said slave relay after a period of time shorter than each of said prescribed periods of time.

2. A system in accordance with claim 1, wherein said slave relay comprises an inductive reactance and said timing circuit comprises the said parallel circuit, resistor and condenser in series REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,555,893 Thompson Oct. 6, 1925 2,080,273 Holmes May 11, 1937 2,182,637 Marbury Dec. 5, 1939 2,205,676 Stansbury et al. June 25, 1940 2,265,203 Six Dec. 9, 1941 2,270,414 Canetta et al Jan. 20, 1942 2,279,849 Warrington Apr. 14, 1942 2,317,888 Cypser Apr. 27, 1943 2,389,564 Sunstein Nov. 20, 1945 FOREIGN PATENTS Number Country Date 341,831 Great Britain Jan. 22, 1931 438,535 Great Britain Nov. 19, 1935 619,250 France Mar. 29, 1927 721,373 France Mar. 2, 1932 

